1. Field of the Invention
This invention pertains to a tool, commonly referred to as a bit, for cutting and stripping insulation from an end portion of flexible conductor wire and for wrapping said end portion around a terminal post in a plurality of successive helical convolutions.
2. Description of the Prior Art
In the art of combination bits for cutting and stripping insulation from the end portion of flexible conductor wire and wrapping the stripped end portion on a terminal a number of inventions have been made pertaining to the configuration of the insulation cutter portion of the bit. U.S. Pat. Nos. 2,807,810; 3,554,243 and 4,076,056 disclose wrapping bits having a substantially U shaped notch formed therein for receiving the insulated wire to sever the insulation partially as withdrawal of the wire is commenced during the wrapping operation.
U.S. Pat. No. 3,696,482 also discloses a substantially U shaped groove for receiving the insulated end portion of a flexible conductor wire and also includes a transverse notch intersecting the groove to form sharp edges for cutting the insulation. U.S. Pat. No. 3,893,491 discloses a movable cutting edge or blade also for partially cutting into the insulation in response to rotation of the bit.
Other prior art bits for cutting and stripping insulation from conductor wires to be wrapped are disclosed in British Pat. No. 1,237,399 and U.S. Pat. Nos. 4,169,310 and 3,781,936, the last mentioned patent being assigned to the assignee of the present invention.
The bits disclosed in the last three patents mentioned above are characterized in that the cutting of the insulation is assisted by the stationary sleeve surrounding the bit which forces the insulated conductor wire into engagement with the bit cutting edge along with the action resulting from the withdrawal movement of the conductor wire as the bit is rotated to commence the wrapping operation. This cooperative action between the sleeve and the insulated end portion of the wire is critical to proper cutting of the insulation without nicking or otherwise damaging the wire and without tearing the insulation to leave a ragged end portion thereof. Even minor nicks or cuts in the conductor wire itself can cause stresses which will result in breakage of the wire during the wrap operation or as a result of attempting to remove the wire from a terminal.
Moreover, the movement of the bit with respect to its stationary sleeve and the cooperation of the cutting edge with the sleeve during initial rotation of the bit has been determined to be critical to proper cutting of the insulation and prevention of jamming of the wire between the bit and the sleeve. In this regard the configuration of the cutting edges on the bit and their angular relationship to the sleeve during the initial rotation of the bit to cut and strip the insulation and commence the wrapping cycle has been determined to be of considerable importance to provide the desired cutting action.
Accordingly in spite of a substantial number of inventions pertaining to improvements in combination conductor wrapping bits a problem of long standing has remained regarding proper insulation cutting and removal.